For 133 years, Greystone Psychiatric Hospital’s five-story main building, with a half-million square feet and walls of granite, has stood like an ominous stone fortress at the edges of Morris Plains, Parsippany and Denville. It was built to last centuries.

The Christie administration will decide if it does.

But whether the building stands or falls, one thing is clear: The land should not be developed. The surrounding towns already are choking on traffic, and their schools and public services are stretched to the breaking point.

Some see the hospital, abandoned and decaying, as a grand structure that must be preserved — the largest structure in Morris County and one of the state’s most historic buildings. Others see it as a potential financial drain at a time when money is tight. Without the money that would be generated by development, is it too costly to save?

Because of Greystone’s historic significance, the state has a responsibility to find out.

The state, which controls the building and some of the land around it, quietly has marketed the site to see if there is any interest from developers. Nearby municipalities have condemned that move, telling state officials and legislators that the towns want the land used only for passive recreation — walking and bike paths and dog parks.

Joining with the anti-housing mayors is Preserve Greystone, a group of Morris County activists who want to save the historic building and get it listed on state and national historic registers. Preserve Greystone envisions low-impact uses: offices for non-profit organizations, a community theater, a museum — “something to benefit the community,” activist Maureen Murray said. Already a smaller Greystone building under renovation is a future home of Arc of Morris County.

The price tag for cleanup and restoration is estimated at $15 million or more. Demolition would cost at least $30 million, “so there’s no sane reason to take it down,” Denville Mayor Ted Hussa said. But it’s possible the state could let the building remain as a ruin, allowing it to crumble, stone by stone, until it’s past the point of salvation.

Instead of allowing Greystone to die that slow death by default, the state should commission a study: Can (and should) Greystone be saved? What would the price be? Where would the money come from? How long until the building, already in disrepair, is beyond saving? What are the possible, plausible uses?

Greystone is a piece of New Jersey’s history. The new administration should find out how much it would cost to preserve it, then, if it’s economically feasible, come up with a plan to do it.